Read up on all we know about Dynasty Warriors 9 here:
Here are some more details (thanks, Games Talk):

When it came down to the next numbered title, in thinking that it would be pointless to follow the same pattern, they figured that a new Dynasty Warriors would be most interesting if it used an open world.

All of China is reproduced. While the Chinese land is a vast one, there are a lot of mountains, so places where battles can take place are limited. For this reason, they’re creating places like Hulao Pass and Zhongyuan in detail.

Know-how is shared within the company. Because the nature of the open world is different from that of Toukiden 2, that technology cannot be used as it is, but that which can be appropriated will be utilized.

They want to change input methods such as Square button for a standard attack and Triangle button for a charge attack. The concept of “being a match for a thousand” will remain, so something like Musou Ranbu will remain.

They’re aiming to make Zhao Cang a comedic character. His weapon is the “Dai Satsu Katana.” It is large and offers dynamic actions. He is a character that combines both excitement and speed, and promises to be fun to use.

I honestly only play the licensed ones now (attack on titan, berserk, hyrule) they seem the best ones for me. I haven't played a DW since 5 I think was fed up of doing the same battles. maybe I try another one at some point.

It's most likely an open world sandbox game, as it was mentioned previously.

Quote:

Dynasty Warriors 9 news coming May 11 -- But we'll probably hear about it on May 9.

After teasing Dynasty Warriors 9 news is coming in May last week, producer Akihiro Suzuki took to Twitter again today to confirm a more specific date of Thursday, May 11.

May 11 is also the date the next issues of Weekly Famitsu and Dengeki PlayStation release, and if the standard pattern follows suit, information from those magazines should leak in the early morning on May 9, eastern time.